Math Problem Statement

what's the right answer

Rajah di sebelah menunjukkan sebahagian daripada graf fungsi kuadratik f(x) = -x^2 + 6x - 5. Garis lurus AB adalah selari dengan paksi-x. Tentukan (a) koordinat titik A, (b) persamaan paksi simetri, (c) koordinat titik B, dan (d) koordinat titik maksimum P.

Solution

The image shows a mathematical problem in Malay, asking about the quadratic function f(x)=x2+6x5f(x) = -x^2 + 6x - 5. A straight line AB is parallel to the x-axis. We are required to determine the following:

(a) Koordinat titik A (Coordinates of point A)

Since point A is on the x-axis, the y-coordinate will be 0. To find the x-coordinate of A, we solve f(x)=0f(x) = 0.

f(x)=x2+6x5=0f(x) = -x^2 + 6x - 5 = 0

Solve this quadratic equation using the quadratic formula:

x=b±b24ac2ax = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}

Here, a=1a = -1, b=6b = 6, and c=5c = -5. Substituting these values:

x=6±624(1)(5)2(1)=6±36202=6±162=6±42x = \frac{-6 \pm \sqrt{6^2 - 4(-1)(-5)}}{2(-1)} = \frac{-6 \pm \sqrt{36 - 20}}{-2} = \frac{-6 \pm \sqrt{16}}{-2} = \frac{-6 \pm 4}{-2}

Thus,

x=6+42=1orx=642=5x = \frac{-6 + 4}{-2} = 1 \quad \text{or} \quad x = \frac{-6 - 4}{-2} = 5

So, point A is at (1,0)(1, 0).

(b) Persamaan paksi simetri (Equation of the axis of symmetry)

The axis of symmetry for a quadratic function f(x)=ax2+bx+cf(x) = ax^2 + bx + c is given by:

x=b2ax = \frac{-b}{2a}

Substitute a=1a = -1 and b=6b = 6:

x=62(1)=3x = \frac{-6}{2(-1)} = 3

Thus, the axis of symmetry is x=3x = 3.

(c) Koordinat titik B (Coordinates of point B)

Since point B is on the same horizontal line (parallel to the x-axis) as point A, and both points share the same y-coordinate, we know B=(5,0)B = (5, 0).

(d) Koordinat titik maksimum P (Coordinates of the maximum point P)

The maximum point (vertex) of the parabola is located at the axis of symmetry, x=3x = 3. To find the y-coordinate, substitute x=3x = 3 into the function f(x)f(x):

f(3)=(3)2+6(3)5=9+185=4f(3) = -(3)^2 + 6(3) - 5 = -9 + 18 - 5 = 4

Thus, the maximum point is P=(3,4)P = (3, 4).

Summary of Answers:

  • (a) Koordinat titik A: (1,0)(1, 0)
  • (b) Persamaan paksi simetri: x=3x = 3
  • (c) Koordinat titik B: (5,0)(5, 0)
  • (d) Koordinat titik maksimum P: (3,4)(3, 4)

Would you like further details or have any questions?


Here are 5 related questions to enhance your understanding:

  1. How does the quadratic formula solve for roots of a quadratic equation?
  2. What is the geometric meaning of the axis of symmetry for a quadratic graph?
  3. Can you derive the vertex formula from completing the square method?
  4. How do you determine if a parabola opens upwards or downwards?
  5. Why do points A and B have the same y-coordinate if the line AB is parallel to the x-axis?

Tip: The vertex of a parabola is a critical point that helps determine the maximum or minimum value of a quadratic function.

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Math Problem Analysis

Mathematical Concepts

Quadratic Functions
Symmetry
Coordinate Geometry

Formulas

Quadratic formula: x = [-b ± sqrt(b^2 - 4ac)] / 2a
Axis of symmetry: x = -b / 2a
Vertex form: f(x) = a(x - h)^2 + k

Theorems

Quadratic formula
Symmetry in parabolas
Vertex formula for quadratic functions

Suitable Grade Level

Grade 10-12